Antarctic Ice Loss

This article describes a report based on satellite observations that records the acceleration of ice loss caused in particularly by warming oceans that are thinning the offshore ice shelves by up to 5 metres annually.

Antarctica is shedding ice at an accelerating rate. Satellites monitoring the state of the White Continent indicate some 200 billion tonnes a year are now being lost to the ocean as a result of melting. This is pushing up global sea levels by 0.6 mm annually – a three-fold increase since 2012 when the last such assessment was undertaken.

Glaciologists usually talk of three distinct regions because they behave slightly differently from each other. In West Antarctica, which is dominated by those marine-terminating glaciers, the assessed losses have climbed from 53 billion to 159 billion tonnes per year over the full period from 1992 to 2017.

On the Antarctic Peninsula, the finger of land that points up to South America, the losses have risen from seven billion to 33 billion tonnes annually. This is largely, say scientists, because the floating ice platforms sitting in front of some glaciers have collapsed, allowing the ice behind to flow faster.

East Antarctica, the greater part of the continent, is the only region to have shown some growth. Much of this region essentially sits out of the ocean and collects its snows over time and is not subject to the same melting forces seen elsewhere. But the gains are likely quite small, running at about five billion tonnes per year.

A second article by two of the researchers elaborates with a little more detail about how almost 3 trillion tonnes of ice have been lost from Antarctica since satellite monitoring began 25 years ago:

We have found that since 1992 Antarctica has lost 2,720 billion tonnes of ice, raising global sea levels by 7.6 mm. What is most concerning, is that almost half of this ice loss has occurred in the past five years. Antarctica is now causing sea levels to rise at a rate of 0.6 mm a year – faster now than at any time in the past 25 years.